Portable pneumatic drill.



PATENTED OCT. 3', 1905.

H. S. POTTER. PORTABLE PNEUMATIC DRILL.

APPLICATION FILED JAN.9,1905.

2 SHEETS-SHEET 1.

Attorney Inventer Per PATENTED OCT. 3, 1905.

H. S, POTTERL PORTABLE PNEUMATIC DRILL.

APPLIOATION rum) JAN. 9.1905.

2 SHEETS-SHEET 2.

IOHB 12514364946550 UNITED STATES HENRY SAMUEL POTTER,

OF BROMLEY, ENGLAND.

PORTABLE PNEUMATIC DRILL.

Specification of Letters Patent.

Patented Oct. 3, 1905.

implication filed Janna 9, 1905. Serial No. 240,345.

To all whom, it min/y concern:

Be it known that I, HENRY SAMUEL POTTER, a subject of the King of Great Britain and Ireland, residing at Bromley, in the county of Kent, England, (whose post-oflice address is 3 Scotts Villas, Heathfield Road, Bromley, in the county of Kent. England,) have invented certain new and useful Improvements in Hand Portable Pneumatic Drills and Like Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.'

This invention consists in improvements in hand portable pneumatic drilling and like machines, which may be employed for drilling,

tapping, tube-expanding, and similar operations.

The invention consists principally in a twocylinder compound-engine drill, in which the motive fluid after acting on the smaller areas of the pistons will pass through distributingvalves to the larger areas of said pistons.

The invention further comprises details of construction and arrangement of parts hereinafter referred to, the object of the invention being to provide a hand portable pneumatic drilling-machine comprising high efficiency in power and working combined with simplicity of construction and comparatively light weight.

In the accompanying drawings, which illustrate a method of carrying out the invention, Figure 1 is a sectional elevation of the machine with one of the cylinders and part of the machine-casing removed. Fig. 2 is a sectional plan of the complete machine, taken on line A B, Fig. 1, showing details of the cylinders and pistons and the connecting-rods to the crank-shafts. as hereinafter described. Fig. 3 is a vertical sectional view of the cylinder shown in Fig. 1, showing details of the piston and its distributing-valve and the connections thereof to the crank-shaft. Fig. 4 is a transverse section on line C D, Fig. 1, and shows the relative arrangement of the two cylinders and their distributing-valve chambers, as well as the throttle-valve and its chamber. Fig. 5 is a detail view of a modified arrangement of the adjustable bearing for the crank-shaft, as hereinafter described. Fig. 6 shows details of the bearings for the ballheads of the connecting-rods of the pistons,

as hereinafter described. Fig. 7 illustrates a detachable and reversible or transposable pinion or gear of the speed-changing arrangement hereinafter described. Fig. 8 is a diagram of the gear-Wheels of the machine as arranged in conjunction with the removable and transposable pinion, whereby change of speed can beobtained, as hereinafter described.

In carrying out the invention the main body 1 of the machine, comprising the fluidpressure cylinders 2 3 and one-half or approximately one-half of the crank and gear chamber or casing, are formed in one casting, the other part t of said gear chamber being formed separate and bolted or otherwise fixed to the main body or cylinder portion.

The cylinders 2 and 3 are arranged side by side and provided with annular hardened-steel liners, respectively, 5 and, 6, and the outer ends of the cylinders are closed by screwcaps 7 8 or by any other known or convenient means. The pistons 9 9 are trunk-pistonsthat is to say, each piston on which the fluidpressure acts has a tubular extension 10 10 of comparatively large diameter which surrounds the connecting-rod 11 11 and works at all times in the forward or inner head 12 12 of the cylinder,the opening in the head through which said tubular extension Works being provided with a neck-bush 13 13 and gland 14: 14: with suitable packing 15 interposed. The connecting-rod 11 of each cylinder is connected to a separate crank-shaft 16 16, which shafts are preferably counterbalanced, as indicated at 17, and each of said shafts carries a pinion or gear 18 18, which drives or forms part of the train of gear-wheels through which the drill is operated. The drill-socket 19(see Fig. 1) is provided with a shoulder or annular projection 20, on which the gear-wheel 21, keyed on said socket, rests, and one half of a ball-race 22 is mounted on said gear-wheel, the other half of the ball-race being suitably mounted in the machine-casing, as shown. An exterior flange or annular projection 23 is also provided adjacent to the forwardor lower end of the drill-socket 19, with which projection 23 a flange or projection 24 on a nut 25, adapted to be screwed onto the part of the casingin which the drill-socket works, engages, thus retaining the drill-socket 19 and gear-wheel 21 thereon in place. A slot 25 is provided in the upper end of the drill-socket, in which slot works the usual pin adapted to be operated by the feed-screw 26 for ejecting the drill from the socket 19. The head 27 of the feed-screw is provided below the bearingpoint with a polygonal or hexagonal enlargement or surface 28, (or is otherwise formed.) so that the usual star-wheel 29 or means employed for operating the feed-screw may be readily disengaged from and reengaged with said surface, the engaging part of the star- Wheel beingofcourse correspond ingly formed. 30 is an externally and internally threaded nut screwed into the upper part of the machine-casing in which the feed-screw 26 works.

The distributing-valves 31 31 are worked by eccentrics 31, (see Fig. 3,) one on each of the crank-shafts,and are in the construction shown piston-valves, with a reduced diameter or necking 32 between the heads of the valve, whereby an annular live-air space is formed in the valve-chambers 33 The construction of the valves 3131 is the same, so that a description of one serves for both. Each valve 31 has ports 34: 35, respectively, at each end lead ing into a central channel 36 in the valve, and said ports 3% 35 are adapted to register, respectively, with inletports 37 and 37, leading into either end ofthe cylinder, thearrangement being such that, (referring to 3,)as su ming that the liveair has been admitted from the annular space in the valve-chamber 33 to the smaller area of the piston 9 (inner side of 1 he pistorrhead) and the piston has completed its stroke in one direction, the valve 31 is shifted, by means of the eccentric 31, so that the port 35 in the valve registers with port 37, and so connects the smaller area of the piston with the central passage 36 in the valve, and at the same time connects the said central passage with the other or larger area of the piston 9(outer side of ,the piston-head) through the ports 34 37, which are caused to register, so that the compressed air passes from the smaller area to the larger area, and thus acts on the larger area and moves the piston in the opposite direction; and when the stroke is completed in this direction the valve has been shifted by the eccentrics 31, so that the annular live-air space 33 in the valve-chamber is opened to the port 37, leading to the smaller area of the piston, and the port 37, leading from the larger area of the piston, is opened to exhaust through the open (outer) end of the valve-chamber 33 or through a convenient exhaust-port. The admission of compressed air to the smaller area of the piston and thence to the larger area and from the latter to exhaust continues as long as the throttle-valve 38 (see Figs. 1 and 4c) is turned to the position for admitting compressed air from the source of supply to the annular live-air space in the valve-chamber 33, formed by the necking or reduced diameter 32 of the valves 31. The throttle-valve 38 consists of a tubular part rotatably mounted in a sleeve or liner 39 in the throttle-valve chamber 40, formed in the machine-casing. The tubular throttle-valve 38 is provided with ports ll 41, and the sleeve 39, in which the throttle-valve works, is also provided with ports 42 4:2, as shown. The outer end of the throttle-valve 33 is provided with a suitable roughened handle 43 in the form of a sleeve, which handle may be made of vulcanite or other suitable material, and the said handle is connected to the throttle-valve by means of a screw or screws, such as 44. The extreme outer end of the throttle-valve 38 is screw-threaded or otherwise suitably formed, so as to provide a convenient means of attaching the compressed-air-supply pipe, and the inner end .of the throttle-valve 38 is closed, as shown in Fig. 1. 38" is an annular shoulder or projection on the throttle-valve 38, and 39 is a tubular nut or collar adapted to be screwed into the throttle-valve chamber 40, as shown, for the purpose of retaining the throttlevalve in its chamber. The usual stop is provided for limiting the rotary movements of the throttle-valve 38, or a spring-stop may be provided to give various port-openings and hold the throttle-valve in any position. \Vith the throttle-valve 38 in the position shown the adu'iission of compressed air from the source of supply to the annular live-air spaces in the valve-chambers is cut off by the wall of the valve 38, as clearly shown in Fig. 4. hen the throttle-valve is turned so as to cause the ports 4:1 41 therein to register with the ports 42 42 in the bushing 39, compressed air will be admitted through the passages 15 45, Fig. 1, in the machine-casing and through the ports 45 in the bushings 33, in which the distributing-valves 33 work, into the annular live-air spaces in the valve-chambers 33, around the neckings or reduced diameters 32 of the distributing-valves, and thence by the reciprocations of the distributingvalves 31 to the high and low pressure heads of the pistons 9 in the cylinders, as above described, the connection of the distributingvalves 31 to their operating eccentrics 31 on the crank-shaft being such that in the working of the engine the compressed air will be admitted to the smaller area or high-pressure head of one of the pistons 9, while at the same time compressed air will be admitted from the smaller area or high-pressure head of the other piston to the larger area or lowpressure head thereof and thence to exhaust, as hereinbefore described.

Each of the connecting-rods 11 is provided with a ball-head 46 and is connected to the piston in the following manner: In the pistonhead there is provided a bearing for the ballhead 46, the lower or inner part or half of the said bearing consisting of two parts 417 47, which are adapted to be placed in position and supported by an annular projection 48 in a recess in the piston-head and retained in posi tion by dowel-pins 4E9 or the like. These two parts 4:7 47 form the lower half of the hearing for the ball-head 46, the upper or outer end of said head being inclosed and retained by a cap or plug 50, screwed or otherwise IIO suitably fixed in the piston-head and provided with a hemispherical recess 51, in which the upper half or part of the ball-head 46 works. The crank-shaft bearings each consist of two rectangular parts or blocks 52 52, suitably bored to receive the end of the crankshaft, and each of the said parts or blocks may be provided with a conical or tapered projection 53 53 on the outside. An adjusting-nut 54 engages one of the said conical projections 53, (see Fig. 3,) the nut 54 being provided with a perforated flange or milled head, in which head a locking pin or plug may engage in a known manner. The conical or tapered projections 53 53*, above referred to, as well as the adjusting-nut 54, may be bored through, thus forming an oiling-channel. Another oiling-channel 56 in the casing or body of the machine may be led to the conical projection 53. A steel disk or plate 57, Fig. 3, covers the outer end of the crank-shaft and its hearing, the said disk being sprung into a suitablyforined recess 58 in the casing of the machine, or the said plate 57 may be otherwise conveniently attached in place. An oil-hole 59 is provided through the plate 57.

Fig. 5 shows an alternative arrangement of the bearing-blocks 52 52 and means of adjustment thereof, the means of adjustment in this case consisting of the pins or bolts 60 60, which are passed through holes or slots in the parts 52 52 of the crank-shaft bearing and screwed into the part X (see Figs. 1 and 5) of the machine body or casing. The bearing at the lower end of the crank-shaft, Fig. 3, preferably consists of the same arrangement of parts 52 52" and adjusting and retaining means therefor, as above described. The inner end of each of the connecting-rods 11, Figs. 1, 2, and 3, is connected to the crank on its respective crank-shaft by means of a split cross-head 63. one-half of which is preferably formed integral with the rod 11. 64 is a sleeve or liner of gun-metal or other material on the crank. These parts may be constructed or arranged in the known or in any convenient manner.

The glands or caps 13, Figs. 2 and 3, screwed into the inner ends of the cylinders are adjustable by means of teeth 65, formed on their outer flanges, with which teeth the teeth on a pinion 66, rotatably mounted in the machinecasing, engage, the said pinion being adapted to be operated, for instance, by means of a screw-driver engaging a groove or recess 66* in the pinion, or the pinion 66 might be operated through its shaft or spindle 67, which projects through on the outside of the machine-casing and may be provided with a suitably-formed head adapted to be rotated by means of a key or the like. 70 is a gear-wheel (see Fig. 1) mounted on a shaft 71, fixed in the machine-casing, with which gear-wheel 70 the pinions 18, one on each of the crank-shafts 16 (see Figs. 2 and 3) engage, so as to transmit movement from the reciprocating pistons 9 through the crank-shaft to the gear-wheel 70. This gear-wheel 70 is keyed on a sleeve 72, rotatably mounted on shaft 71, on the outer end of which sleeve 72 the pinion 73 is fixed or formed, (see Fig. 1,) and the teeth of this pinion 73 engage the teeth of the gearwheel 21, keyed on the tool-socket 19, as hereinbefore described. 74, Fig. 1, is a sleeve or liner of gun-metal or other suitable material.

In assembling the tool-socket 19 and gearwheel 21 in the machine, the part4 of the machine-casing being detached from the part 1 and the cap 25 having been removed from the part 4 of the casing, the gear-wheel 21, with the lower half of the ball-bearing 22 attached, is slipped into its chamber in the part 4 of the casing, and the tool-socket is then passed through the opening in the lower end of part 4 of the casing, so that the shoulder 20 on the said socket engages the gear-wheel 21, whereupon the cap 25 is screwed onto its threaded part of the casing, so that the flange 24 on said cap engaging with the flange 23 on the tool-socketwill retain the parts in position. Referring to Figs. 3, 7, and 8, which illustrate the speed-changing arrangement hereinbefore referred to, in constructing the machine comprising this device it would be arranged that the gear wheels or pinions 18 would have the positions, as shown in Fig. 8, in relation to the gear-wheel 70, instead of the positions shown in Fig. 2. The pinions 18, (see Figs. 3 and 7,) are each provided with an extension (which as shown is a tubular extension) 18, and the end of the crank-shafts 16 are prolonged, as shown in Fig. 3, an extension of the machine-casing being also provided, Fig. 3, as a housing for the extended end of the crank-shaft. With this arrangement in order to change the speed at which the drill will be driven it is only necessary to slip. the pinion 18 (or pinions, as thecase may be) off the crank-shaft and replace it thereon in a reverse position to that shown in Fig. 3that is to say, it would be placed on the crank-shaft in the position shown in Fig. 7, with the pinion 18 in the lower position, in which its teeth will engage with the teeth of the gear: wheel 21, whereby an increased speed will be obtained. In order to reverse or transpose the pinion 18, as described, it is only necessary to detach the part 4 of the machine-casing from the part 1 (see Fig. 1)

and then slip the pinion 18 off the shaft 16 and replace it thereon in the reversed position, the part 4 of the casing being then reattached to the part 1, or as an alternative the part of the machine-easing in which the extension of the crank-shaft 16 works, Fig. 3, may be provided with or formed as a screwcap which can be screwed onto and oi the main part of the casing.

The outer end of the shaft 71 is extended through the machine casing and suitably formed, so as to provide a convenient means of attaching a right-angle gear or other suitable mechanism for transmitting motion from the drill-gearing at an angle to the normal motion given to the tool-socket 19. Spaces 75 (which are preferably annular spaces) are provided in each of the piston-heads and act as what may be called negative spaces, the object being to obtain a higher mean effective pressure on a low-pressure head or larger area of the piston, and to thereby obviate undue reduction in temperature, which might cause freezing at the exhaust-ports.

As an alternative construction instead of arranging the cylinders side by side, as hereinbefore mentioned, the cylinders may be arranged at right angles to each other, or at any other suitable angle, and in this case only one crank-shaft may be employed instead of the two previously referred to.

Although the above description has been made with reference to a two-cylinder drill, yet the improvements generally are not necessarily limited to a pneumatic drill comprising a two-cylinder engine. For instance, a convenient form of breast-drill can be constructed by employing only one of the cylinders and pistons with its di'stributing-valve in conjunction with suitable gearing for operating the drill. Further, variations may be made in the details as described and shown without departing from the main features of the invention.

What I claim as my invention, and desire to secure by Letters Patent, is-

The combination, with a shaft or socket for operating the tool, feed mechanism for moving the said shaft or socket longitudinally, and a detachable casing supporting the said parts; of a main casing having the said detachable casing secured to it, two power-cylinders carried by the said main casing, two stuffingboXes also carried by the said main casing, pistons slidable in the said cylinders and provided with trunks which are slidable in the said stuffing-boxes,two crank-shafts journaled in the said casings at their connecting joint, eonnecting-rods between the said crank-shafts and pistons, toothed drivingwheels operatively connecting the said crank-shafts with the said shaft or socket, and valve mechanism for admitting pressure fluid first to the front ends of the said cylinders and thence to their rear ends in which it operates expansively.

In testimony whereof I affix my signaturein presence of two witnesses.

HENRY SAMUEL POTTER.

\Vitnesses:

LESLIE G. \VHEELER, EUs'rAcn H. BARKER. 

